Signal transmitting device for vehicles



Dec. 11, 1951 F. GAGNAIRE 2,578,347

SIGNAL TRANSMITTING DEVICE FOR VEHICLES Filed July 29, 1947 3Sheets-Sheet 1 Dec. 11, 1951 F. GAGNAIRE 2,578,347

SIGNAL TRANSMITTING DEVICE FOR VEHICLES Filed July 29, 1947 3SheetsSheet 2 F. GAGNAIRE SIGNAL TRANSMITTING DEVICE FOR VEHICLES Dec.11,1951

3 Sheets-Sheet 5 Filed July 29, 1947 Patented Dec. 11, 1951 SIGNALTRANSMITTING DEVICE FOR VEHICLES Francois Gagnaire, Lyon, FranceApplication July 29, 1947, Serial No. 784,500 In France April 4, 1944Section 1, Public Law 690, August 8, 1948 Patent expires April 4, 1964 7Claims. 1

My invention relates to the transmission to a vehicle driver of signalsfrom a following vehicle.

It is well-known that it is dimcult for the driver of a truck or othervehicle of large dimensions to perceive signals from another vehiclewishing to pass in front. Acoustic signals are drowned in the noises 01the truck and luminous signals are only visible at night. Arrangementshave been proposed for transmitting the sound from the rear of thevehicle to the drivers seat but either they are simple trumpets whichhave not proved altogether satisfactory. or they are devices which tendto deaten the driver by transmitting all the noises of the truckincluding that of the exhaust which is particularly intense at the rear.If in lieu of transmitting sounds to the driver one seeks to give him anindication from an apparatus set in action by luminous signais, theapparatus may respond unsuitably to daylight, for instance when the sunis low on the horizon, or when going downhill.

It has been proposed to obviate these inconveniences by providing on theovertaking car an emitter emitting acoustic signals of definitefrequencies and on the truck or the like a receiver tuned to thecorresponding frequencies which are inaudible or almost inaudible, or byemploying wireless transmission between the two cars. But these devicesrequire a particular arrangement on the overtaking car.

My invention permits on the contrary to use on the overtaking car theusual horns or like acoustic devices, or the headlights.

According to my invention a system for transmitting to a vehicle driversignals from a following vehicle comprises a totalising apparatussubmitted to the action of a zeroing mechanism which tends to return thesaid apparatus to its position of rest at a limited speed, a signalreeeiver adapted to deliver an impulse to the said apparatus for eachsignal received, and an indicating device set in action by thetotalising apparatus when the latter has received a sufllciently highnumber of impulses in a suillciently short time.

In the accompanying drawings:

Fig. 1 is a diagrammatic view of an arrangement in accordance with theinvention having a hydraulic totaliser.

Figs. 2 to 5 indicate diagrammatically various mechanical arrangementsof a mechanical totaliser apparatus.

Figs. 6 to 8 show electric totaliser apparatus. Fig. 9 shows a totalizerapparatus operated thermally.

Hg.10isadiagramoiadeviceensuringa durable indication of the signalsreceived and wherein the release of this indication is combined with theemission of a reply signal.

In Fig. 1 acoustic signals are received by a microphone i which sends acurrent into an amplifier 2 which in turn supplies a relay 3. The lattercloses a circuit comprising a battery 4 and a coil 5 raising a plungercore 8 connected to a rod 1 carrying two small spheres 8 and 9 formingopposite valves cooperating oppositely with the same seating Ill withina vertical tube ll. Tube II is connected above the seat II to areservoir I! by a pipe l3 and it supplies in turn a vessel It by way ofa pipe i5 opening beneath the said seating. This vessel It is providedwith a small outlet l6 regulated by a needle il. It encloses a float itwhich, when the level rises sufflciently, actuates a contact I! closinga circuit which comprises the battery 4 and a lamp or other indicatingapparatus 2| disposed adjacent the driver.

On each signal received by microphone I relay l closes the circuit andcoil 5 raises rod 1 causing sphere 9 to close from beneath the passagewhich in the position of rest is closed from above by sphere 8. In thismovement a certain quantity of liquid passes down through tube ii andenters vessel N. If the successive impulses received by relay 3 aresufliciently close to each other, the quantity of liquid received byvessel It within a given time is higher than the quan tity lost byoutlet It; the level rises within the said vessel It and float i8actuates the indicator 20.

It will be understood that with a proper adiustment the totalisingapparatus will operate indicator 20 when the driver of the vehicledesiring to pass the truck operates his warning note repeatedly for asuflicient length of time. But it will be insensitive to a noise whichis isolated even it this is of long duration.

Relay 3 should however be suitably insensitive to impulses having a veryrapid succession, such as those which may result from the noise of theexhaust. This result can be obtained by giving to the movable part ofrelay 3 a sumciently high moment of inertia so that it will not be ableto follow very short impulses very close to each other and will remaineither open or closed according as the impulses are feeble or strong,the latter case being exceptional, since short impulses involve limitedquantities of electricity. It could also be arranged that the amplifler2 forms a rectifier or is associated with a r ctifier in such mannerthat the supply current'of the said relay may be direct current. It isthen suflicient to provide a condenser 2| mounted in shunt on the coilof the relay to damp current impulses of high frequency and to obtainwith such impulses a continuous current which leaves relay 3 open orclosed continuously. Finally the coil of the relay may also be providedwith short-circuited windings or rings giving it a very high timeconstant in the known manner; such a coil has a very high reactancewhereby the relay is much more sensitive to impulses of low frequencythan to those of high frequency. Obviously these various means may becombined.

For a better understanding of my invention it may be remarked that in asuccession of acoustic or luminous signals two kinds of frequencies maybe involved: first, the frequency of the sound or light used for thesignal, for instance 500 periods per second in the case of an acousticsignal; sec-- end, the frequency of the succession of signals, forinstance 100 per minute. The first frequency has formed thediscriminating means in the prior art, while it is immaterial with myinvention which is only concerned with the second one. And as myinvention is more conveniently carried into practice by means ofacous'.ic signals delivered by repeated actuation of a push-button orthe like, this frequency will thereafter be termed keying frequency ofthe signal.

From the above it follows that my apparatus is finally sensitive to awide band of keying frequencies, which eliminates isolated sounds or theexhaust noise (at 1000 R. P. M. the exhaust frequency of a four-cylinderengine is 2000) The receiver I may be a luminous receiver with aphotoelectric cell sensitive to rays emanating from the headlights ofvehicles which are asking to pass. In this case without any particulararrangement of the amplifier the current received by the relay 3 is adirect current without the need for a rectifier. If desired tworeceivers respectively light and sound sensitive may act in parallel tocontrol relay 3.

The amplifier 2 is not absolutely necessary and may be dispensed whenrelay 3 is sensitive to unamp'ifled microphone currents.

Fig. 2 shows a mechanical construction of a totalising apparatus. Thecore 5 actuates a lever 22 carryi g a pawl 23 which cooperates with aratchet 24 carried by a wheel 25 loose on'a shaft 26. Wheel 25 isreturned by a spring 21 and carries a boss 23 adapted to actuate thecontact l9. It carries also a pawl 29 which on the return movement ofthe wheel 25 under the action of the spring 21 drives a ratchet wheel 30keyed on shaft 24. The latter carries a wheel 3| which engages aclockwork mechanism 32 of any suitable construction diagrammaticallyindicated by a mere pinion so as not to complicate the drawing.

At each impulse pawl 23 causes wheel 25 to advance against the action ofthe spring 21. The latter tends to return it but this return can only beeffected by driving a clockwork movement, that is to say ata relativelyslow speed so that with sufllciently numerous and rapid impulses boss 23may actuate the contact l3.

The inertia of lever 22 and of core i may be sufllcient to eliminateimpulses of too high keying frequency even apart from thecharacteristics of the relay 3.

The arrangement shown in Fig. 3 provides a pivoted sector 25" havingtee'h 24 which teeth are engaged and moved downwardly by a pawl 23 whenthe solenoid 5 is energized. A spring 21 4 provides a constant forcetending to raise the toothed end of the sector 24, and this raisingeffect is partially opposed by a dash pot 33 which regulates the rate ofrising thereof, but does not oppose lowering of the toothed sector 24when acted upon by the pawl 23.

In Fig. 4 the core 6 operates an arm 34 which by means of a pawl 35drives a wheel 36 which is prevented by a second pawl 31 from turningbackwards. Wheel 36 drives a shaft 38 on which there is mounted arotating clockwork movement 39 of the kind used on delaying apparatuscontrollin electric switches. It is known that these movements arereturned by an internal spring to a fixed angular position on the shaftwhich carries them but that this return is delayed while the delayingmechanism does not operate when they are moved from the set positionagainst the return spring. The contact I! comprises here a beak in onewith the shaft and a finger in one with the casing of the movement, thecurrent being supplied to these two parts by suitable brushes 40 and 4!.

The current impulses received by the coil 5 cause the contact beak toturn in the clockwise direction while the corresponding finger followsin the same direction but at slow speed. Impulses having a suflicientkeying frequency produce closing of the contact l9 as in the precedinginstance.

In Fig. 5 the wheel 36 and the clockwork movement here representeddiagrammatically by a pinion 32 as in Fig. 2 are connected by adifferential gearing 42, 43 the planetary train 43 of which is returnedby a spring 44 and may moreover actuate the contact I9 when it has beensufiiciently moved from its position of rest against the action of thesaid spring. Here again it will be understood that the impulses tend tocause the planetary train 43 to rotate in clockwise direction while thespring 44 tends to return it in the opposite direction but driving themovement 42 which imposes a slow speed. The operation thus remains thesame as in the preceding instance.

In the apparatus according to Fig. 6 the relay 3' is arranged to sendonly a short current impulse at each impulse which it receives from theamplifier 2. For this purpose the fixed contact 311 for the circuit isactuated so as to touch the movable bar only during a fraction ofmovement of the latter. 0n the otherhand the coil 5 is disposed around ahydraulic vessel 42 in which the core 0 is vertically movable; core 5 isconnected to a washer 43 forming a pision which is not completely tightin the vessel 42. Vessel 42 is filled with oil or other liquid. Washer43 forms an automatic valve permitting rapid upward movement butensuring slow downward movement of the core 6.

At each short current impulse received by relay 3 core 3 rises by asmall amount, but between the successive impulses it falls slowlyretarded by washer 43. Here again a proper keying frequency causes core6 to rise sufficiently to actuate the contact IS.

The short current impulse necessary for each signal may also be obtainedby interposing a transformer or a condenser between a relay 3 such asthat shown in Fig. 1 and the said coil 5. Fig. 7 indicates such anarrangement and makes it clear that the coil 5 receives only a shortcurrent impulse on the closing and opening of relay 3. The same resultwould be obtained by arranging a condenser shunted by suitableresistance in series with the coil 5.

Fig. 8 shows an electric totalising apparatus auras? constituted by acondenser 44 of large capacity (an electrolytic condenser for example)charged by a relay 3' of the kind described in Fig. 6 with a resistanceor reactance l5 interposed so that the charge may be aperiodic.Condenser 44 is discharged on a relay .6 having a very high resistancewhich operates the contact l9. At each impulse coming from the relay 3the condenser 44 receives an elementary charge which escapes by thewinding of the relay 46 in the form of a current of very small intensityand insufficient to actuate the relay. If the impulses succeed oneano'her with a sumcient keying frequency the successive chargesaccumulate, the voltage rises and the intensity of the discharge currentincreases until it is sufllcient to actuate the relay 6 and close thecontact l9.

Here again an ordinary relay could be used in lieu of the relay 3' byinterposing a transformer but it would be necessary moreover to providea rectifying device so as to allow only asingle charging wave for thesecondary of the transformer to pass.

In Fig. 9 the totalising apparatus is a thermal relay with a hot wirefed by very short current impulses produced by a relay 3a of the kindillustrated in Figs. 6 and 8, but which can also be produced by atransformer. An isolated impulse is insufiicient for the hot wire 45' toclose the contact I9 but several successive impulses sumciently close toeach other may produce this result. The condenser 44 has been retainedso as to accumulate a considerable charge of electricity at each closureof the circuit by relay 3a and avoid having to employ too fine a wire46', but this is obviously not essential.

It is clear that in lieu of a hot wire there could be used a bimetalstrip combined with a small heating resistance. It is also clear thatthe thermal relay may be suitably compensated so as to be insensitive tovariations in external temperature.

The thermal relay permits easy regulation of the keying frequencylimits. It is sufllcient to isolate it more or less in order to vary thespeed of cooling of the sensitive element.

It will be understood that the examples of totalising apparatus could bemultiplied without departure from the scope of the invention.

In the preceding examples of construction the indicating apparatus 20only operates while the contact 19 is closed. This relatively shortindication does not persist and may pass unperceived by the driver.

Fig. 10 shows a device remedying this disadvantage. The circuit ofapparatus 20 comprises a relay 41 the armature of which is arranged inorder to close the said circuit (self-adhering relay). Contact I! isdisposed in shunt with the contact operated by the armature. With suchan arrangement a momentary operation of contact I9 is suflicient tocause relay H to close in a permanent manner the circuit of apparatus20. The driver is thus warned with certainty. In order to cause theindication to disappear it is sufilcient in a known manner to press thecontact-separating stud 48. As shown stud 48 is double and comprises acontact controlling a reply signal 49 so as to warn the driver of thefollowing vehicle that his call has been heard and that he is to beallowed to pass. Owing to this arrangement the driver of the truckcannot fail to respond and until he has done so, the driver of thefollowing vehicle knows that his signal should be repeated in order tobe effective.

Other mechanism ensuring the permanence of operation of the indicator 2|once it has been closed may be imagined. For example a mechanicalreleasing mechanism may be provided which it would be necessary to resetbeing combined with the reply signal It.

I claim:

1. A system for installation in a vehicle to operate indicating means insaid vehicle when excited by signals transmitted from a followingvehicle, said signals being repetitive and being within a limitedoperative range with respect to length of signal and spacingtherebetween, said system comprising a signal receiver having means forconverting the individually received signals independent of theirlengths into pulses of constant length and amplitude; a differentialtotalizer having means for increasing the totalizer contentincrementally for each pulse received and having means for decreasingthe totalizer content at a fixed and continuous rate, the rate of thedecreasing means being so related to the rate of the converted pulseswhen received at a rate within the operative range as to permit thetotalizer to reach'a predetermined totalized content; and an indicatoractuated by said totalizer when it attains said predetermined content.

2. In a system as set forth in claim 1, damping means in said receiverto prevent actuation of said totalizer increasing means by signals whichrepeat at a rate outside of and above said operative range.

3. In a system as set forth in claim 1, said converting means comprisinga relay in said receiver, said relay having an armature adapted to beclosed by each signal received; a contact spaced from the closedposition of the armature and adapted to be brushed thereby during eachclosing motion; and a source of constant voltage between the relay andsaid increasing means whereby a pulse is transmitted from said source tothe increasing means as the armature brushes the contact.

4. In a system as set forth in claim 1, said differential totalizercomprising a liquid collecting vessel; a float in said vessel responsiveto the liquid level therein; a switch closed by said float when itreaches a predetermined level, the switch operating said indicator: saidincreasing means comprising a liquid delivering device adapted todeliver a. fixed quantity of liquid to the vessel for each pulsereceived; and said decreasing means comprising a restricted orifice inthe vessel to permit outflow of liquid therefrom at a limited rate.

5. In a system as set forth in claim 1, said pulses being electrical innature and said difcooled by natural heat losses.

6. In a system as set forth in claim 5, said electrical impulses beingunidirectional in character, an electrical condenser across said heatresponsive element to smooth out surges in said impulses reaching theelement.

'7. In a system as set forth in claim 1, said pulses being electricaland unidirectional in nature, and said differential totalizer comprisingan electric condenser adapted to be charged by said pulses; and avoltage responsive relay amw 7 in parallel with said condenser andadapted to Number slowly discharge the condenser at a fixed rate,2,176,742 said relay when closed actuating said indicator. 2,394,788FRANCOIS GAGNAIRE. 2,507,359

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